The Middle Sect
Li Daochun, the founder of the Middle sect, was a Daoist in the Yuan dynasty who was also known as Yun Chanzi in Daoist circles. As a second generation disciple of Bai Yuchan, he put forward his own theory of Inner Alchemy which combined the Three Doctrines, stressing Harmony and Keeping to the Middle. His theory of Inner Alchemy was so distinctive that it was called the Middle sect of Inner Alchemy by Daoism in later periods, although it was actually neither a religious organization nor an Inner Alchemy sect.
Li Daochun wrote books such as Essays on Harmony and The Essence of the Book of Changes from the Three Heavens, which helped to create a new method for Inner Alchemy. His ideas were inherited and advocated by Yin Gaodi, a Daoist scholar of the Ming dynasty, and by Huang Yuanji of the Qing dynasty. In his book Pointers on Spiritual Nature and Bodily Life, Yin Gaodi discussed essentials for Keeping to the Middle, stressing the Integration of the Three Doctrines. In his book Quotations from the Hall of Blissful Teaching, Huang Yuanji studied methods for Inner Alchemy, stressing the effect of Keeping to the Middle. In the General Summary of Perfect Men and Sects, a Daoist book kept in the White Cloud Temple, this method of Inner Alchemy was called the "Middle sect" or "Anterior Heaven sect".